I’ve been distracted with other projects so apologies for the lack of updates. I’ve been using the curved LCD for a while now so here’s the final method:
Start with a lense, ground into the right shape, the method in Part 1 worked well enough. I used perspex but in hindsight, a lens made from cast epoxy resin would have been easier and far less work.
I masked the lens off with black spray paint to cover the edges of the LCD. It’s important to use plastic safe paint as there’s a chemical reaction between certain spirits/solvents and perspex that causes it to self destruct.
Masked lens with lcd split out.
The important bit!
The main issues were bonding the lens and contamination of the backlight assembly. To avoid contamination of the backlight, I very carefully separated the LCD from the backlight, and flipped it over. You need to be careful doing this, the ribbon cable is really fragile. I also masked off the exposed backlight assembly to protect it from dust and fingerprints.
This is the setup I used to prep for bonding. I made sure everything was forensically clean and laid it all out in advance. I used white spirit to clean the lens and the screen. White spirit is the only solvent I have found that doesn’t cause any issues, it also has a long evaporation time which helps get everything smudge free.
The bonding step needs to be absolutely right and being prepared will save you from having to panic and scrabble around. I used a blusher brush for the final clean. I noticed that for the absolutely final step, if you huff on the surfaces first and then use a fine blusher brush, it removes any final streaks.
Preparation is key!
I used LOCA TP-2500 adhesive, it is really viscous and flow is key. It has a unique odour and thanks to a pavlovian reaction, it smells of failure and disappointment to me. 🙂
I mounted the LCD facing upwards on a flat surface and then bonded the lens on top. This gives you a good view of the screen and you can check for bubbles, grit, dust etc as you go. I applied the loca to the LCD in an X shape which causes the LOCA to run to each corner first and squeeze out from the middle. I noticed a small bubble on the first application but lifted it, put an extra dot of LOCA in the middle and pressed down until the bubble was pushed to the edges and out. this step is really messy which is why masking is so important.
I used some spare UV bulbs to cure the LOCA and the hardest part for me was to leave it while it cured. I blasted it with UV for a couple of hours just to be sure.
Fire UV lamps, maximum yield, full strength! 🙂
LOCA weeps for a long, long time and I ruined few backlights by being impatient. I ended up leaving the assembly open and on an absorbent cloth for three days (The longest three days ever!) if you don’t, this happens:
When the LOCA has eventually finished weeping, now is the ideal time to perform some clean up of the screen. I used a plastic spudger and some white spirit to get rid of the mess and gave it a final treatment with a clean blusher brush.
So close to success!!
Reassembly and Test.
When I was absolutely sure, I reassembled the final unit and tested it. I laid it on my trusty +2, powered it up, and success! I treated myself to a listen of the Agent X theme tune while I double checked the unit but the curve is definitely there!
This was a pretty tricky project but I like the idea of being able to reliably do it again rather than trust to luck. It isn’t a CRT but it’s pretty close. Ideally, this method could be scaled up to larger screens specifically for retro computing. If a custom driver board could be produced for retro systems it would have direct control of the pixels and would save the need for an OSSC etc. The power usage would also be much lower of a CRT.
Here’s some footage of it in action: